An empirical model for natural convection heat transfer for film-boiling condition has been developed for volumetrically heated particulate debris beds when flooded with water at the top of the bed. The model has been derived from the quenching data generated in the POMECO facility located at KTH, Stockholm. A dry-out model is also developed for countercurrent flooding limiting condition when the heat generating saturated debris bed is flooded with water from the top. The model is in good agreement with the experimental data over a wide range of particle size and Porosity as compared to the existing models. The implication of the models with respect to quenching of porous debris bed formed during postulated severe accident condition is discussed.
